1. Field of the Invention
This invention is an adjustable light scattering rod.
2. Description of the Prior Art
Calibration instruments used for calibrating light scattering analyzers are known in the art. For example, in U.S. Pat. No. 3,742,899 to David K. Longhenry there is provided a device which determines whether a light scattering photometering analyzer is accurately performing. This is accomplished by passing a nested group of wedge-shape sheets through the analyzer. These sample sheets of highly transparent and gray neutral filter glasses have been previously measured by a standard invention instrument to be sure they fall into the operating range of the instrument under investigation. In this way standard readings can be used to determine if the instrument is properly operating within the range of the samples.
Another device is the atmospheric pollution monitor disclosed in U.S. Pat. No. 3,860,818 to A. F. Stalder et al. In the instrument disclosed therein, filters mounted in a rotating chopper are used to provide a range of opacity which can be used to compare samples.
In this invention, the adjustable invention scatterer rod provides a way to periodically check the calibration of a light scattering dust monitor (monitor). Initially the monitor is calibrated by adjusting its electrical gain until its readout meter agrees with the known concentration of the aerosol being sampled. Next, the scatterer rod is inserted into the light cone of the monitor to cause scattering of light. The scatterer rod is then adjusted by its calibrating screw until the monitor meter readout is the same as that of the known concentration. This adjusted scatterer rod then becomes the reference which can be used as a field calibrator checker. The prior art completely fails to suggest or disclose such an adjustable scatter calibration rod for use with a light scattering device.